VALLEY — Carotenoids are yellow, orange, and red pigments present in fruits and vegetables. There are more than 600 carotenoids; the most commonly consumed and well-studied carotenoids include beta-carotene, alpha-carotene, beta-cryptoxanthin, lycopene, lutein, and zeaxanthin.
Some carotenoids are converted to vitamin A in the body — beta-carotene, alpha-carotene, and beta-cryptoxanthin for example; these carotenoids are important for proper immune function. Carotenoids give the skin a healthy glow and defend the body’s tissues against oxidative damage, helping to prevent chronic diseases and premature aging.
The richer your diet in carotenoids, the greater the likelihood of longer telomeres (DNA sequences at the end of chromosomes). The length of telomeres is thought to be an indicator of biological aging—the longer the telomere length, the slower the aging of cells. Many studies have connected a healthy diet and lifestyle behaviors to longer telomeres.
Data from 3660 U.S. adults were analyzed for serum carotenoids and leukocyte telomere length. When they compared the groups with the lowest and highest levels of each carotenoid, they saw 5-8 percent longer telomeres for the groups with the highest alpha-carotene, beta-carotene, and beta-cryptoxanthin levels. Researchers think that higher carotenoid levels may work by protecting telomeric DNA from oxidative damage, leading to protection against aging and chronic diseases.
Lycopene, a carotenoid found in tomatoes, grapefruit, and papaya, is concentrated in the prostate, where it has potent anti-cancer effects. Lycopene-rich foods also protect the skin against ultraviolet radiation from the sun. In one study, after twelve weeks of tomato supplementation by healthy women, reddening of the skin, mitochondrial DNA damage, and markers of skin aging due to UV exposure were reduced.
Lutein and zeaxanthin, which are found in leafy greens like kale and collards, are the only known carotenoids located in the human retina. Light must pass through lutein and zeaxanthin before being transmitted to the cells that send visual information to the brain. These carotenoids filter some of the blue light that enters the retina, and this function protects the eye from damage and improves several aspects of visual performance.
Alpha-carotene is an excellent marker of high-nutrient vegetable intake, since dark green and orange colored vegetables are the richest sources of alpha carotene. In one notable study, individuals with the highest blood levels of alpha-carotene had a 39 percent decrease in risk of death compared to those with the lowest serum alpha-carotene.
Get your carotenoids from colorful vegetables and fruits. Carotenoid supplements have consistently failed to produce beneficial effects in clinical trials. In fact, supplemental carotenoids are likely to be harmful. For example, high serum beta-carotene has been associated with decreased lung cancer risk, but beta-carotene supplements may actually increase the risk of lung cancer, especially in smokers.
In addition to their own beneficial effects, carotenoids like alpha-carotene, lycopene, and lutein in the blood are markers indicating the intake of thousands of additional phytochemicals from fruits and vegetables that work synergistically to keep the body healthy. Keep in mind that carotenoid absorption during a meal requires the presence of fat — one of the reasons to use nut and seed-based dressings on salads and raw vegetables.
Dr. Fuhrman is a #1 New York Times best-selling author and a board certified family physician specializing in lifestyle and nutritional medicine. The Eat To Live Cookbook offers over 200 unique disease-fighting delicious recipes and his newest book, The End of Heart Disease, offers a detailed plan to prevent and reverse heart disease using a nutrient-dense, plant-rich (NDPR) eating style. Visit his informative website at DrFuhrman.com. Submit your questions and comments about this column directly to [email protected]